1. Field
Embodiments relate to a cylindrical secondary battery.
2. Description of the Related Art
In general, unlike primary batteries that are not rechargeable, secondary batteries are rechargeable and dischargeable. Secondary batteries are used in small-sized devices, e.g., cellular phones, notebook computers, and camcorders, or medium- and large-sized devices, e.g., electric vehicles, electric bicycles, and uninterruptible power supplies (UPSs). Among secondary batteries, a lithium (Li) battery has a higher energy density per unit weight than, e.g., a Li-cadmium (Cd) battery or a Li-hydrogen (H) battery, and thus is widely used.
Li batteries generally use Li-based oxide as a positive electrode active material and a carbon material as a negative electrode active material. According to the type of electrolyte, Li batteries are classified into a liquid electrolyte battery and a polymer electrolyte battery. A battery using a liquid electrolyte is referred to as a Li ion battery and a battery using a polymer electrolyte is referred to as a Li polymer battery. According to the shape of a can for accommodating a battery unit, Li batteries may be classified into cylindrical and rectangular batteries and a pouch battery having flexibility.
A general cylindrical battery includes a battery unit, a can for accommodating the battery unit, and a cap assembly for sealing an opening of the can. The battery unit includes a positive electrode plate, a negative electrode plate, and a separator interposed between the positive and negative electrode plates. The positive electrode plate is electrically connected to a positive electrode tab and the negative electrode plate is electrically connected to a negative electrode tab. The positive and negative electrode tabs are respectively electrically connected to the cap assembly and the can.
In this case, the positive electrode tab is connected to the cap assembly through a penetration hole of an insulation plate on an upper portion of the battery unit.